Ink jet recording apparatus having residual quantity detection unit and residual quantity detection method thereof

Abstract

According to the present invention, there is provided an ink jet recording apparatus for recording an image on a recording medium by discharging ink to the surface of the recording medium, wherein ink is reserved in an ink tank including a negative pressure generating member, such as an absorber and a foaming member, and a function of accurately detecting the residual quantity such that depletion to a predetermined level can be detected is realized. Light emitted by a photointerrupter is allowed to pass through a portion of a wall surface of the ink tank made of transparent plastic or the like which is transmissible with respect to detection light emitted by the photointerrupter to detect change in the light reflectance in the boundary portion between the wall surface and the ink absorber. In accordance with reflectance obtained in a case where no ink exists in the detected portion and that obtained in a case where ink exists, the residual quantity of ink can be detected.

What is claimed is: 
     
       1. An ink jet recording apparatus having a recording head for discharging ink through a nozzle thereof and an ink tank for supplying ink to said recording head, said ink tank having a supply port for supplying ink to said recording head and including a negative pressure generating member for generating negative pressure so as to discharge ink from said nozzle of said recording head to print an image on a recording medium, said ink jet recording apparatus comprising: light emitting means for emitting light to a portion of a wall surface in said ink tank at which said negative pressure generating member is located;   light receiving means for receiving reflected light of light emitted by said light emitting means; and   discrimination means for discriminating a state of residual quantity of ink in said ink tank in accordance with a quantity of light received by said light receiving means,   wherein light which is received by said light receiving means includes light reflected by an inside wall of said ink tank and light reflected by said negative pressure generating member.   
     
     
       2. An ink jet recording apparatus according to claim 1, wherein said light receiving means receives light emitted by said light emitting means and reflected by said wall surface, a boundary surface between said wall surface and said negative pressure generating member and said negative pressure generating member.   
     
     
       3. An ink jet recording apparatus according to claim 1, wherein wavelength of light emitted by said light emitting means is the wavelength which penetrates ink in said ink tank.   
     
     
       4. An ink jet recording apparatus according to claim 1, wherein said wall surface of said ink tank to which light emitted by said light emitting means is a bottom portion of said ink tank.   
     
     
       5. An ink jet recording apparatus according to claim 1, wherein said discrimination means discriminates that the residual quantity of ink in said ink tank is smaller than a predetermined quantity when the quantity of light received by said light receiving means is larger than a predetermined threshold.   
     
     
       6. An ink jet recording apparatus according to claim 1, wherein said discrimination means discriminates the residual quantity state of ink in said ink tank in accordance with change in the quantity of light received by said light receiving means.   
     
     
       7. An ink jet recording apparatus according to claim 1 further comprising: reflectance calculating means for calculating the reflectance in accordance with light emitted by said light emitting means and light received by said light receiving means,   wherein said discrimination means discriminates the residual quantity state of ink in said ink tank in accordance with said reflectance.   
     
     
       8. An ink jet recording apparatus according to claim 1 further comprising display means for displaying the residual quantity state of ink in accordance with discrimination performed by said discrimination means. 
     
     
       9. An ink jet recording apparatus according to claim 1 further comprising: recording control means for interrupting a recording operation performed by said recording head when said discrimination means has discriminated that the residual quantity state of ink in said ink tank has been reduced to a level lower than a predetermined residual quantity.   
     
     
       10. An ink jet recording apparatus according to claim 1 further comprising: a carriage on which both recording head and said ink tank can be mounted;   scanning means for scanning said carriage relatively to a recording medium; and   control means for causing said scanning means to scan said carriage to a position, at which said light emitting means and said light receiving means face said wall surface of said ink tank, to discriminate the residual quantity state of ink in said ink tank.   
     
     
       11. An ink jet recording apparatus according to claim 10, wherein a plurality of said recording heads are provided, a plurality of said ink tanks are provided to correspond to said plurality of said recording heads, and said control means causes said scanning means to make the wall surface of each of said ink tanks to face said light emitting means and said light receiving means, and   said discrimination means sequentially discriminates the residual quantity state of ink in said plurality of said ink tanks.   
     
     
       12. An ink jet recording apparatus according to claim 1, wherein said discrimination means causes said scanning means to relatively scan said carriage, said light emitting means and said light receiving means to perform discrimination at a plurality of positions of said wall surface in accordance with reflected light.   
     
     
       13. An ink jet recording apparatus according to claim 1 further comprising: ink tank detection means for detecting whether or not said ink tank exists in accordance with light received by said light receiving means.   
     
     
       14. An ink jet recording apparatus according to claim 1, wherein said light emitting means and said light receiving means are formed integrally into a photointerrupter.   
     
     
       15. An ink jet recording apparatus according to claim 1 further comprising adjustment means which is capable of adjusting the quantity of light which is emitted by said light emitting means. 
     
     
       16. An ink jet recording apparatus according to claim 15, wherein said light emitting means emits light in response to an electric signal applied thereto, and   said adjustment means modulates the pulse width of said electric signal to be supplied to said light emitting means to enable the quantity of light, which is emitted by said light emitting means, to be adjusted.   
     
     
       17. An ink jet recording apparatus according to claim 16, wherein said electric signal is a signal in the form of a pulse, and said adjustment means adjusts the width of said pulse.   
     
     
       18. An ink jet recording apparatus according to claim 16 further comprising: reflecting portion so disposed as to be capable of reflecting light emitted by said light emitting portion to said light receiving portion; and   means for causing said adjustment means to modulate said electric signal to be supplied to said light emitting means in response to light reflected by said reflecting portion in such a manner that the quantity of light received by said light receiving means is made to be constant.   
     
     
       19. An ink jet recording apparatus according to claim 16 further comprising: storage means for storing information formed on the basis of said drive signal modulated by said adjustment means,   wherein said discrimination means subjects information formed on the basis of the quantity of light emitted to said wall surface of said ink tank, reflected by the same and received by said receiving means and information stored in said storage means to a comparison to discriminate the residual quantity state of ink in said ink tank.   
     
     
       20. An ink jet recording apparatus according to claim 1 further comprising: correction means for correcting a signal formed on the basis of the quantity of light received by said light receiving means.   
     
     
       21. An ink jet recording apparatus according to claim 1, wherein said recording head applies thermal energy to ink to cause ink to change the state thereof due to heat so that ink is discharged due to pressure generated due to change in the state of ink.   
     
     
       22. An ink jet recording apparatus according to claim 1, wherein said light emitting means and said light receiving means are comprised by a photointerrupt, the photointerrupt provided individually from a carriage, wherein the carriage has an opening portion for permitting light emitted from said light emitting means to pass through and a reflecting plate for reflecting said emitted light, and   wherein sensitivities of said light emitting means and said light receiving means are controlled at a capping position at which a distance from the carriage to the photointerrupt is constant.   
     
     
       23. An ink jet recording apparatus according to claim 1, wherein said light receiving means receives, through the wall surface of said ink tank, a change in light reflectance of a boundary portion between the wall surface and the negative pressure generating member at a predetermined timing to output obtained data, and wherein said discrimination means compares a result of the n-th (n is an integer which satisfies n≧2) output and a result of the (n-1)-th output, or results of outputs to (n-1)-th output, and discriminates that the residual quantity of ink in said ink tank has been reduced if the comparison indicates a change larger than a predetermined value α.   
     
     
       24. An ink jet recording apparatus according to claim 1, further comprising: a carriage on which said ink tank and said recording head are mounted; and   means for vertically moving the carriage to a plurality of positions to be adaptable to a thickness of the recording medium,   wherein said light receiving means receives, through a wall surface of said ink tank, a change in light reflectance of a boundary portion between the wall surface and the negative pressure generating member at a predetermined timing to output obtained data, and   wherein said discrimination means compares a result of the n-th (n is an integer which satisfies n≧2) output and a result of the (n-1)-th output, or results of outputs to (n-1)-th output, subjects the received light reflectance to a predetermined calculation corresponding to a position of the carriage, and discriminates that the residual quantity of ink in said ink tank has been reduced if the comparison indicates a change larger than a predetermined value α.   
     
     
       25. A method of detecting residual quantity of ink in an ink tank of an ink jet recording apparatus, which has a recording head for discharging ink through a nozzle thereof and an ink accommodating portion for supplying ink to said recording head, said ink tank having a supply port for supplying ink to said recording head and including a negative pressure generating member for generating negative pressure so as to discharge ink from said nozzle of said recording head to print an image on a recording medium, said method of detecting residual quantity of ink comprising: a light emitting step for emitting light from light emitting means to a portion of a wall surface in said ink tank at which said negative pressure generating member is located;   a light receiving step for receiving reflected light of light emitted in said light emitting step by light receiving means; and   a discrimination step for discriminating a state of residual quantity of ink in said ink tank in accordance with a quantity of light received in said light receiving step,   wherein said light which is received in said light receiving step includes light reflected by an inside wall of said ink tank and light reflected by said negative pressure generating member.   
     
     
       26. A method of detecting residual quantity of ink according to claim 25, wherein said light receiving step is a step for receiving light emitted in said light emitting step and reflected by said wall surface, a boundary surface between said wall surface and said negative pressure generating member and said negative pressure generating member.   
     
     
       27. A method of detecting residual quantity of ink according to claim 25, wherein wavelength of light emitted in said light emitting step is the wavelength which penetrates ink in said ink tank.   
     
     
       28. A method of detecting residual quantity of ink according to claim 25, wherein said wall surface of said ink tank to which light is emitted in said light emitting step is a bottom portion of said ink tank.   
     
     
       29. A method of detecting residual quantity of ink according to claim 25, wherein said discrimination step is a step for discriminating that the residual quantity of ink in said ink tank is smaller than a predetermined quantity when the quantity of light received in said light receiving step is larger than a predetermined threshold.   
     
     
       30. A method of detecting residual quantity of ink according to claim 25, wherein said discrimination step is a step for discriminating the residual quantity state of ink in said ink tank in accordance with change in the quantity of light received in said light receiving step.   
     
     
       31. A method of detecting residual quantity of ink according to claim 25 further comprising: a reflectance calculating step for calculating the reflectance in accordance with light emitted in said light emitting step and light received in said light receiving step,   wherein said discrimination step is a step for discriminating the residual quantity state of ink in said ink tank in accordance with said reflectance.   
     
     
       32. A method of detecting residual quantity of ink according to claim 25 further comprising: a display step for displaying the residual quantity state of ink in accordance with discrimination performed in said discrimination step.   
     
     
       33. A method of detecting residual quantity of ink according to claim 25 further comprising: a recording control step for interrupting a recording operation performed by said recording head when a discrimination has been performed in said discrimination step that the residual quantity state of ink in said ink tank has been reduced to a level lower than a predetermined residual quantity.   
     
     
       34. A method of detecting residual quantity of ink according to claim 25, wherein said ink jet recording apparatus to which said method is adapted comprises a carriage on which both recording head and said ink tank can be mounted; and   scanning means for scanning said carriage relatively to a recording medium, and said method of detecting residual quantity of ink further comprising the step of: a control step for causing said scanning means to scan said carriage to a position, at which said light emitting means and said light receiving means face said wall surface of said ink tank, to discriminate the residual quantity state of ink in said ink tank.     
     
     
       35. A method of detecting residual quantity of ink according to claim 34, wherein said ink jet recording apparatus to which said method is adapted comprises a plurality of said recording heads, a plurality of said ink tanks are provided to correspond to said plurality of said recording heads,   said control step is a step for causing said scanning means to make the wall surface of each of said ink tanks to face said light emitting means and said light receiving means, and   said discrimination step is a step for sequentially discriminating the residual quantity state of ink in said plurality of said ink tanks.   
     
     
       36. A method of detecting residual quantity of ink according to claim 25, wherein said discrimination step is a step for causing said scanning means to relatively scan said carriage, said light emitting means and said light receiving means to perform discrimination at a plurality of positions of said wall surface in accordance with reflected light.   
     
     
       37. A method of detecting residual quantity of ink according to claim 25 further comprising: an ink tank detection step for detecting whether or not said ink tank exists in accordance with light received by said light receiving means.   
     
     
       38. A method of detecting residual quantity of ink according to claim 25, wherein said light emitting means and said light receiving means are formed integrally into a photointerrupter.   
     
     
       39. A method of detecting residual quantity of ink according to claim 25 further comprising: an adjustment step in which the quantity of light emitted by said light emitting means can be adjusted.   
     
     
       40. A method of detecting residual quantity of ink according to claim 39, wherein said light emitting means emits light in response to an electric signal applied thereto, and   said adjustment step is a step for modulating the pulse width of said electric signal to be supplied to said light emitting means to enable the quantity of light, which is emitted by said light emitting means, to be adjusted.   
     
     
       41. A method of detecting residual quantity of ink according to claim 40, wherein said electric signal is a signal in the form of a pulse, and said adjustment step is a step for adjusting the width of said pulse.   
     
     
       42. A method of detecting residual quantity of ink according to claim 40, wherein said ink jet recording apparatus to which said method is adapted has a reflecting portion so disposed as to be capable of reflecting light emitted by said light emitting means to said light receiving means; and   said adjustment step is a step for modulating said electric signal to be supplied to said light emitting means in response to light reflected by said reflecting portion in such a manner that the quantity of light received by said light receiving means is made to be constant.   
     
     
       43. A method of detecting residual quantity of ink according to claim 40 further comprising: a storage step for storing information formed on the basis of said drive signal modulated in said adjustment step,   wherein said discrimination step is a step for subjecting information formed on the basis of the quantity of light emitted to said wall surface of said ink tank, reflected by the same and received by said receiving means and information stored in said storage means to a comparison to discriminate the residual quantity state of ink in said ink tank.   
     
     
       44. A method of detecting residual quantity of ink according to claim 25 further comprising: a correction step for correcting a signal formed on the basis of the quantity of light received by said light receiving means.   
     
     
       45. A method of detecting residual quantity of ink according to claim 25, wherein said recording head applies thermal energy to ink to cause ink to change the state thereof due to heat so that ink is discharged due to pressure generated due to change in the state of ink.   
     
     
       46. A method according to claim 25, wherein, in said light receiving step, a quantity of reflected light is detected at a predetermined timing to transmit detected data, and wherein, in said discrimination step, a result of the n-th (n as an integer which satisfies n≧2) output and a result of the (n-1)-th output, or results of output (n-1)-th output, are compared, and it is discriminated that the residual quantity of ink in said ink tank has been reduced if the comparison indicates a change larger than a predetermined value α.   
     
     
       47. A method according to claim 25, wherein in said light receiving step, a quantity of reflected light is detected at a predetermined timing to transmit detected data, and wherein, in said discrimination step, a result of the n-th (n as an integer which satisfies n≧2) output and a result of the (n-1)-th output, or results of output (n-1)-th output, are compared, the detected light reflectance is subjected to a predetermined calculation corresponding to a position of a carriage on which said ink tank and said recording head are mounted, and it is discriminated that the residual quantity of ink in said ink tank has been reduced if the comparison indicates a change larger than a predetermined value α.